Gui Zhi, also known as Cinnamon twig or Ramulus Cinnamomi, is a traditional Chinese herb that releases the exterior and assists Yang. Diving into the biochemistry of Gui Zhi’s actions can explain its’ powerful effects.
Gui Zhi’s Neuroprotective Effects
An animal study in 2020 looked at how Gui Zhi is protective against brain damage. The researchers first administered a neurotoxic herb to inhibit the prefrontal cortex in rats and then administered Gui Zhi to explore its’ neuroprotective effects.
To evaluate the activity in the prefrontal cortex, the study measured the levels of neurotransmitters GABA, glycine, and aspartic acid. The neurotoxic herb enhanced the levels of these neurotransmitters while Gui Zhi decreased these levels. The reduction in neurotransmitters suggests that Gui Zhi could be a neuroprotective agent against neurotoxicity.
The brain as a box
Gui Zhi as an Antidepressant
A clinical trial in 2005 compared the effects of an herbal formula containing Gui Zhi to a conventional anti-depressant. Ninety peri- and post-menopausal women who presented with both insomnia and mood disorders participated in the study.
The study separated the participants in two groups: one group received a prescription anti-depressant while the other received the Chinese medicine formula. The formula was Chai-hu-gui-zhi-gan-jiang-tang.
To evaluate mood, researchers measured plasma interleukin-6 (IL-6) and soluble interleukin-6 receptor (sIL-6R) levels before and after three months of the therapies. Higher IL-6 levels play a role in the stress responses seen in depressive disorders. Furthermore, studies have found high IL-6 levels to also be predictive of depressive symptoms.
The results of the study showed that the herbal formula group had significantly lower levels of plasma IL-6 and sIL-6R than the anti-depressant group. The findings suggest that Gui Zhi has the potential to decrease stress pathways involved in depression. Further studies are needed to evaluate the participants’ perceived experience of depression.
How Gui Zhi Affects Fever
In an animal study in 2003, researchers induced fever in rats. The intention was to evaluate whether Gui Zhi could inhibit the rise in temperature.
The researchers induced a fever by manipulating the EP3 receptor in rats. Researchers discovered that Gui Zhi interrupted the temperature increase by acting directly against down-stream events of the EP3 receptor.
The researchers additionally evaluated whether individual components of Gui Zhi could do the same as the complete herb. The active compounds cinnamaldehyde and total glucoside of paeony inhibited the fever while cinnamic acid did not. This study helped to identify what components of Gui Zhi can act against a fever.
Gui Zhi’s Role in Cardiac Health
A recent in vitro study in 2021 looked at a decoction of Gui Zhi (GZD) for hypertension. The decoction included Gui Zhi, Baishao, Gancao, Shengjiang, and Dazao. While classical Chinese herbal medicine has widely utilized Gui Zhi for hypertension, the specific mechanisms are not completely known.
The study found Gui Zhi’s active ingredients to act on 56 targets in hypertension. To narrow it down, researchers focused on five targets: interleukin-6 (IL-6), C-C motif chemokine 2 (CCL2), IL-1beta, matrix metalloproteinase 2 (MMP-2), and MMP-9. These targets can help explain why the formula is an effective therapy for hypertension.
In animal models, several studies have measured GZD’s clinical effects.
In 2014, an animal study found GZD to improve heart rate variability and regulate the vagus nerve. The vagus nerve is an essential player in the autonomic nervous system. Damage in both the autonomic nervous system and high heart rate variability are both factors in cardiac disease and hypertension.
In 2020, rat models showed regulation of the sympathetic nervous system and improved cardiac outcomes with GZD. Compared with a control, the GZD significantly inhibited inflammatory infiltration and collagen deposition of myocardial injury and improved cardiac function. The researchers concluded that these findings suggest that GZD could delay the progression of heart failure.
Gui Zhi in Neuropathy
Additoinally, a retrospective study in 2019 explored a Chinese herbal formula with Gui Zhi for painful diabetic peripheral neuropathy. The decoction contained Huangqi, Wuwu, and Gui Zhi.
The study enrolled 30 patients with moderate to severe painful peripheral diabetic neuropathy. All patients had reported that pharmaceuticals were unable to relieve their pain. The patients received the formula twice a day for six months and rated their symptoms along the way.
The researcher found the herbal formula to significantly improve their overall pain rating, most notably limb pain, limb numbness, and insomnia.
While these outcomes were not compared to a control, this study suggests the potential for the formula to be an effective therapy for painful diabetic peripheral neuropathy when conventional medications are unsuccessful.
Patient experiencing peripheral neuropathy
Diabetes Pathways Targeted by Gui Zhi
Researchers in 2019 assessed which active compounds in the formula GSZD containing Gui Zhi acts on pathways in Diabetes Mellitus. This Chinese herbal formula contains Shaoyao, Zhimu, and Gui Zhi.
The study identified 275 potential active compounds with 57 possible pathways involved in Diabetes. These pathways included those involved in insulin signaling and glucose metabolic process regulation. The researchers concluded that this identification is a strategy for evaluating the effectiveness of GZSD on the multiple targets and pathways within Diabetes.
A Gui Zhi Formula for Rheumatoid Arthritis
A systemic review in 2017 evaluated thirteen randomized controlled trials where GSZD was utilized as a therapy for Rheumatoid Arthritis. Among these trials, the GSZD formula varied, GSZD was sometimes given with conventional mediation, and the control groups were either a placebo or conventional medication.
When compared to placebo, the GZSD was found to be three to six times more effective than conventional medication for some studies! The analysis could not reach a definitive conclusion due to the variability between the studies however, the formula should be considered as an effective therapy for Rheumatoid Arthritis. More research is necessary to understand and further implications of GZSD on Rheumatoid Arthritis.
In this review, we have touched on pathways that Gui Zhi effects and explained how the herb can be utilized as a therapeutic tool in health conditions. If you are curious, there is numerous data available on the internet!